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serial: altera: set RRDY flag also without irq 

The UART can be operated without an irq. In this case a timer is setup
that regularily calls altera_uart_interrupt(). The receiving part
depends on pp->imr having the bit ALTERA_UART_STATUS_RRDY_MSK set,
otherwise altera_uart_rx_chars() is never called. So ensure that the bit
gets set (disguised as ALTERA_UART_CONTROL_RRDY_MSK) by not returning
early from altera_uart_startup() if port->irq is 0.

This doesn't affect the hardware as the ALTERA_UART_CONTROL_RRDY_MSK bit
isn't actually written to the control register.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Uwe Kleine-König 2018-01-25 14:30:45 +01:00 committed by Greg Kroah-Hartman
parent 2ea6ad8bc6
commit eefadcbca7
1 changed files with 9 additions and 9 deletions
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18
drivers/tty/serial/altera_uart.c
View File

@ -321,20 +321,20 @@ static int altera_uart_startup(struct uart_port *port)
{
struct altera_uart *pp = container_of(port, struct altera_uart, port);
unsigned long flags;
int ret;
if (!port->irq) {
timer_setup(&pp->tmr, altera_uart_timer, 0);
mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
return 0;
}
} else {
int ret;
ret = request_irq(port->irq, altera_uart_interrupt, 0,
DRV_NAME, port);
if (ret) {
pr_err(DRV_NAME ": unable to attach Altera UART %d "
"interrupt vector=%d\n", port->line, port->irq);
return ret;
ret = request_irq(port->irq, altera_uart_interrupt, 0,
DRV_NAME, port);
if (ret) {
pr_err(DRV_NAME ": unable to attach Altera UART %d "
"interrupt vector=%d\n", port->line, port->irq);
return ret;
}
}
spin_lock_irqsave(&port->lock, flags);